"Shame," said Victoria, looking a tad disappointed - even though she correctly spelled the word.

The Big Bang Theory doesn't have a monopoly on nerd TV humour, not the way the Bee is going. The preliminary rounds were just as memorable for comedic sentences as for any spellings or misspellings of words like "catalepsy" or "mastodon."

"Andre promised to regale his friends with tales of his entire odyssey," Bailly told one speller, "but it turned out just to be a 45-minute story about the time he got lost in Costco for 35 minutes."

After the laughter subsided, Lillian Allingham of Hockessin, Delaware, completed that bit of spelling "odyssey" by correctly spelling the word.

Forty-six spellers advanced to the semifinals using scores from onstage words and a computerised spelling-vocabulary test, their achievements vying for attention with jokes about the George Foreman grill and the game Minesweeper.

More humour is on tap for the final day of competition on Thursday, when the 87th champion in Bee history will be crowned in prime time.

"The objective is just to kind of cut the tension," Bailly said. "You know, the sentence is probably the piece of information that has the least clear purpose, and so it's a place where we can have a little fun and relax a little bit."

It began as an experiment in 2009, when Bee Director Paige Kimble hired a pair of Hollywood comedy writers to lighten up the proceedings.

The inside connection: Jeffrey Blitz, who directed the documentary Spellbound more than a decade ago, had won an Emmy that year for directing episodes of The Office.

Nevertheless, Kimble was initially so uncertain about the idea that she didn't even tell broadcast partner ESPN.

"Among other things, we didn't know if it was really going to be funny, so why put yourself out there?" she said. "We instantly got a very positive reaction. Over time, kids have come to appreciate it and expect it."

Some of the one-liners are written ahead of time, but the comedy writers are also in the auditorium and will come up with sentences during the competition, based on what they observe in the personalities of the spellers and the potential for the words themselves.

Bee officials approve the sentences and send them to Bailly, who has final say over whether they are read - since he's the voice behind the ad hoc stand-up routine.